BRIEF NOTE ON TODAY’S WEATHER: Easterly to northeasterly winds have banked some cloudiness and moisture against the mountains on this Friday. So we have a cooler day ahead than recent days, with some fog and drizzle, especially this morning. END UPDATE
The name Hurricane Sandy makes me think of a dear friend, Sandy LaCorte (pictured here), now working at the National Weather Service in Wilmington, N.C. Sandy, a proud North Carolina-Asheville graduate, monitored the radar in my van and built up team morale during the 2007 and 2008 Virginia Tech storm chase trips (yes, she was Kathryn Prociv‘s predecessor) , in which we saw a combined 12-15 tornadoes. Now she has what is turning into an infamous storm named after her — and likely never again, as the storm will almost certainly have its name retired. A shout-out to Sandy, closely monitoring the storm that bears her name as it whips up waves on Wilmington’s coastline in the next few days. I wrote about her in this 2008 column linked here.
I’ll start with my 7 key points about Sandy/Frankenstorm/Snoreastercane, or whatever you want to call it, for Southwest Virginia:
(1) Confidence is HIGH that there will be major to historic East Coast storm system as Hurricane Sandy is absorbed into a polar trough dipping southward. Details on where exactly it tracks and what effects it produces on particular locations remains uncertain. Landfall between Virginia’s Eastern Shore and the eastern end of Long Island, N.Y. seems most likely.
(2) Southwest Virginia can expect windy weather from Sunday night through Tuesday, and possibly longer, next week. Wind gusts of more than 40 mph are likely; wind gusts of more than 60 mph may be possible during at least some of that time frame, depending on the storm’s track. The closer the center tracks to us, the more wind there will be.
(3) The threat of snow, possibly even heavy snow, has increased some for Southwest Virginia, as forecast models, particularly the European, are depicting a farther south track that could pivot the core of colder air and waves of moisture into the region Monday and Tuesday. As is typical, the best chances of significant snow will be in higher elevations and west of Roanoke, but the system is so dynamic, it is possible that snow will extend farther south and east and into lower elevations.
(4) The storm will heavily affect multiple Eastern U.S. states. Coastal flooding from high waves — exacerbated by a full moon — is possible from North Carolina to Maine. Unlike a hurricane with a tight inner core, high winds with a strong extratropical low will extend hundreds of miles from the storm center. There will be torrential rain, too — probably well to our north and east.
(5) Southwest Virginians should be prepared for possible power outages next week. Even 40 mph wind gusts may be enough to cause damage to trees, and blow limbs into power lines, due to remaining leaves on the trees and possible leftover weakened or loosened limbs from the June 29 derecho and other summer storms. Wind gusts of 60 mph and/or heavy wet snow would cause much more numerous and widespread power outages.
(6) The fall colors are absolutely gorgeous in spots. Enjoy them Friday and Saturday before they blow away.
(7) It might be a good idea to find the snow shovels and test the snow blower this weekend, just in case. You may not need them for another 2 months (or 4, if it’s like last winter), but then again ….
Let’s talk about this snow thing, since the wind is just about a given, rain is unlikely to be a huge factor here, and snow is by far the number one topic of interest on this blog. The European and DGEX models (sort of an extended North American Model) have led the way over the past 24 hours on suggesting snowfall — and maybe piles of it — may occur in Southwest Virginia on Monday and Tuesday. This is because these models track the low west-northwest over the Delmarva Peninsula toward southern Pennsylvania at just the right angle to allow it to swirl both Arctic air and thick moisure around its west and southwest sides into our region. This is NOT the usual way we get snow in our region, but of course, this is not a typical storm system, this is a once-in-a-lifetime atmospheric setup.
Some reasons to be skeptical of the bigger snowfall amounts posted. (1) Westerly winds over the mountains go downslope into much of our region, and this can dry out low-level moisture. (2) Most models presume a 10:1 liquid to snow ratio; the snow that would fall in this setup would almost certainly have denser water content, probably more of a 4:1 to 8:1 snow. (3) The ground is VERY warm, coming out of a summer and a week of 70s to low 80s this week. You know I’ve said before that warm ground is a very overrated factor in not expecting snow to stick, but this is a little different than even last Feb. 19 with a day in the 60s and a mild winter leading into a 5-9 inch snowfall. It will take very heavy snow and surface temperatures falling to very near freezing, if not below, to overcome a high melt rate — and even then, it would probably slowly melt from underneath, so total on the ground would be less than the total that falls. (4) Is the moisture and/or cold air really going to be as deep as modeled coming around the backside of the storm? (5) How much modifying warmth does injecting a tropical system into this storm system bring?
On that last point — the last run of the European model, the 12Z, actually takes the storm center into Northern Virginia. As a result, the warm core of the storm actually cuts off snow totals to the northeast — almost edging into our neck of the woods, and driving the heaviest core of snow west of Interstate 77. Because of how this storm is expected to wrap up, it may indeed occur that somewhere to the south has heavy snow while someone north has rain on Monday. Danville could have snow while Winchester has rain. Lynchburg might have snow while it’s raining up U.S. 29 at Charlottesville. Heck, it might snow at Raleigh while it’s raining in Pennsylvania. There is at least one precedent for this kind of topsy-turvy rain/snow division — the Appalachian Storm of 1950, which became so wrapped up over the Ohio Valley it was driving a cold front north through Pennsylvania while pushing a warm front southwest through Michigan. Southwest Virginia got 6-10 inches in that event, while eastern Kentucky, western West Virginia and southern Ohio had snow in feet. That storm, like this one, was a surface low pulled northwest from the coast into a polar trough. But it didn’t have a hurricane feeding into it.
Reason No. 6 to be skeptical: The storm track may just end up too far north for it to rotate much moisture into our region for snow. Reason No. 7: The storm track might even go too far south and cross through central Virginia, and more and more of our area from northeast to southwest would get a windy rainstorm.
All that said: I think we’re going to see our first snowflakes next week. Even if the storm tracks farther north, the circulation around it will probably be enough for some upslope snow showers to creep over the mountains, maybe even later in the week than the Monday-Tuesday timeframe. I do think this heavy snow angle is worth continuing to follow closely, because you know a system coming off the ocean with tropical moisture is going to have a lot it can fling at us, and if it’s cold enough, as many models show, there is a chance it could be a huge, paralyzing dump of slushy white for at least part, if not all, of our region.
So … as it stands now … big East Coast storm, just about certain. Windy for us: Yes. Snowflakes for us: probably. Big snow for us: maybe.